Gas Safety and Carbon Monoxide Poisoning
According to HSE statistics, around 20 people die each year from carbon monoxide poisoning caused by gas appliances and flues that have not been properly installed, maintained or that are poorly ventilated. While these fatalities were to homeowners, carbon monoxide poisoning also poses a risk to site workers.
This is illustrated by the case of Alpha Group Security Ltd, a Glasgow-based security firm, which was fined £7,000 following the carbon monoxide poisoning of a man employed as a security guard on a construction site in the city. He died at an on-site flat used as a base for employees in February 2008. A portable power generator was used inside the flat, but the deceased had not been provided with proper instructions on its safe use. The generator was operated inside the flat without appropriate ventilation and the employee was overcome by a fatal build-up of carbon monoxide fumes.
Alpha Group Security Ltd pleaded guilty to breaching ss.2(1), 2 and 33 (a) of the Health and Safety at Work, etc Act 1974 (HSWA). Clyde Valley Housing Association Ltd, which subcontracted the security company, was fined £70,000 separately after pleading guilty to a charge under s.3(1) of the HSWA.
The Gas Safety (Installation and Use) Regulations 1998 place duties on gas consumers, engineers, suppliers and landlords. Ventilation and flues are covered by the Building Regulations.
By law, anyone carrying out work on gas appliances or fittings as part of their business must be competent and a Gas Safe Registered engineer.
What is carbon monoxide?
Carbon monoxide is a colourless, odourless, tasteless, poisonous gas produced by incomplete burning of carbon-based fuels, including gas, oil, wood and coal.
When carbon monoxide enters the body, it prevents the blood from bringing oxygen to cells, tissues, and organs, and it can quickly kill without warning. Early symptoms of carbon monoxide poisoning can be confused with food poisoning, viral infections, flu or simple tiredness. These include drowsiness, headaches, breathlessness and nausea.
Protecting site workers
Among other, more obvious, hazardous activities, construction workers may be at risk from on-site carbon monoxide poisoning. Inadequately ventilated liquefied petroleum gas (LPG) cookers and heaters can produce carbon monoxide. There is also the risk that flammable gas may escape from leaking cylinders, which can ignite or explode without warning.
Using properly maintained electrical equipment can eliminate the risks associated with LPG appliances. If LPG must be used, the risks can be reduced by:
- Using and storing the cylinders in safe, well-ventilated places outside site accommodation or in purpose-built, ventilated storage areas
- Ensuring that appliances have been properly installed, checked and maintained by a competent person
- Providing adequate combustion ventilation with fixed grilles at high and low level (a window that can be opened is not adequate, as it is likely to be closed in cold weather)
- Checking that the ventilation provided is not blocked, e.g. by newspaper or rags in cold weather to stop draughts
- Checking that cylinders are properly turned off when not in use
- Using wall- or ceiling-mounted carbon monoxide detectors.
Members of the public have died from carbon monoxide poisoning after refurbishment work has disrupted gas flues or ventilation systems, causing the gas to build up in occupied premises.
The impact of refurbishment work on existing gas-fired systems must be identified during the planning stage and managed throughout the project. A competent gas engineer should be involved where there is any likelihood that refurbishment work will affect gas-fired systems.
Preventing carbon monoxide exposure
It is essential to ensure that any work carried out in relation to gas appliances in domestic or commercial premises (e.g. installation or maintenance) is undertaken by a Gas Safe Registered engineer who is competent in that area of work. The Gas Safe Register is the only gas engineer registration scheme approved by the HSE under the Gas Safety (Installation and Use) Regulations 1998.
There should always be enough fresh air in the room containing the gas appliance. If there is a chimney or a flue, checks need to be carried out to ensure it is not blocked up and that vents are not covered. If there are appliances that use other fossil fuels, they should be serviced and maintained by a competent person.
Carbon monoxide alarms
The HSE strongly recommends the use of audible carbon monoxide alarms as a useful back-up precaution, although these must not be regarded as a substitute for the proper installation and maintenance of gas appliances by a Gas Safe Registered engineer.
Before purchasing a carbon monoxide alarm, the buyer must ensure it complies with the standard BS EN 50291: 2001 Electrical Apparatus for the Detection of Carbon Monoxide in Domestic Premises, and carries a British or European approval mark. Carbon monoxide alarms should be installed, checked and serviced in line with the manufacturer’s instructions.
People asleep are particularly at risk from carbon monoxide poisoning, because they may not be aware of early carbon monoxide symptoms until it is too late. Having an audible carbon monoxide alarm could wake them and save their life.
Warning signs to look out for
Although carbon monoxide is a colourless, odourless and tasteless gas, signs that indicate incomplete combustion is occurring (resulting in the production of carbon monoxide) include:
- Yellow or orange rather than blue flames (apart from fuel effect fires or flueless appliances which display this colour flame)
- Soot or yellow/brown staining around or on appliances
- Pilot lights that frequently blow out
- Increased condensation inside windows.
The following steps should be taken if a carbon monoxide leak from an appliance is suspected.
- Switch off the appliance and do not reuse it until remedial action has been taken
- Shut off the gas supply at the meter control valve (if its whereabouts is known)
- If gas continues to escape, call the National Grid on the Gas Emergency Freephone Number (0800 111 999)
- Open all doors and windows to ventilate the room; do not sleep in it
- Seek medical attention urgently and tell your medical practitioner that you believe your symptoms may be related to carbon monoxide poisoning; request either a blood and/or breath sample be taken (note: carbon monoxide quickly leaves the blood and tests may be inaccurate if taken more than four hours after exposure has ceased)
- Contact a Gas Safe Registered engineer immediately to make repairs.